Gou Bao

Gou Bao is not a plant but a rare animal concretion: a bezoar or gastrolith formed in the stomach or biliary tract of the domestic dog, Canis lupus familiaris Linnaeus (family Canidae). The substance occurs sporadically and unpredictably in slaughtered or deceased dogs, where it appears as a rounded to ovoid stony mass, typically 1-3 cm across, with a yellow-brown to greyish-black surface, a hard but somewhat layered internal structure on section, and a faintly bitter or grassy taste. Genuine specimens are scarce and historically commanded a high price in the materia medica trade. The bezoar is collected at slaughter, washed, dried in the shade, and stored whole or pulverised for use. Its composition is variable, comprising organic and mineral concretions analogous to other animal bezoars.